High power-factor AC/DC converter with parallel power processing

Abstract

The present invention is an AC/DC (alternating current to direct current) converter. The converter contains two semi-stages. One is the boost-flyback semi-stage that has excellent self-PFC property when operating in DCM even though the boost output is close to the peak value of the line voltage. Moreover, it allows part input power transferred to load directly through the flyback path so the power conversion efficiency is improved. The other one is the D/DC semi-stage that provides another parallel power flow path and improves the regulation speed.

1. A high power-factor AC/DC converter, comprising:
 a. full-wave rectifier, said full-wave rectifier having an input, said input connected to a single phase AC voltage source; 
 b. boost-flyback semi-stage, said boost-flyback semi-stage comprising an input, a boost output and a flyback output; 
 c. bulk capacitor, said bulk capacitor connected to said boost output of said boost-flyback semi-stage; 
 d. DC/DC semi-stage, said DC/DC semi-stage being selected from a group consisting of a forward module and a flyback module, said DC/DC semi-stage module having an input connected to said bulk capacitor; 
 e. first load, said first load connected to said flyback output of said boost-flyback semi-stage and said output of said DC/DC semi-stage; and 
 f. control switch, said control switch connected to said boost-flyback semi-stage and said DC/DC semi-stage. 
 
   
   
     2. The AC/DC converter according to  claim 1 ,
 wherein said boost-flyback semi stage is obtained by serially connected a boost sub-circuit and a flyback sub-circuit. 
 
   
   
     3. The AC/DC converter according to  claim 2 ,
 wherein said flyback sub-circuit comprises a first diode, a first transformer, a second diode, and a first capacitor. 
 
   
   
     4. The AC/DC converter according to  claim 2 ,
 wherein said boost sub-circuit comprises a first inductance, a third diode, and a second capacitor. 
 
   
   
     5. The AC/DC converter according to  claim 2 ,
 wherein the charging paths of said boost sub-circuit and said flyback sub-circuit are serially connected together. 
 
   
   
     6. The AC/DC converter according to  claim 1 ,
 wherein said DC/DC semi-stage module is a flyback semi-stage module. 
 
   
   
     7. The AC/DC converter according to  claim 1 ,
 wherein said control switch is a power transistor. 
 
   
   
     8. The AC/DC converter according to  claim 1 ,
 wherein said control switch is a metal-oxide semiconductor field-effect transistor (MOSFET). 
 
   
   
     9. The AC/DC converter according to  claim 1 ,
 wherein said DC/DC semi-stage module is a forward module, comprising a second transformer, a fourth diode, a fifth diode and a second inductance.